# 定义一个失血模型的纯数据类。
class User:
    __username = 'Woniu'
    __password = '12345'
    __phone = '13812345678'
    __balance = 0

    def set_username(self, username):
        self.__username = username

    def get_username(self):
        return self.__username


if __name__ == '__main__':
    user = User()
    user.set_username('Hello')
    print(user.get_username())

